Combined Heat and Power in Greater Copenhagen

Combined Heat and Power Projects in Greater Copenhagen (CTR/VEKS)

H. C. Mortensen
The Metropolitan Copenhagen Heating Transmission Company

Introduction

The sharp drop in total national fuel consumption for space heating began in the early 1970s and continues to the present. A major reason for this has been the rapidly growing number of connections to the collective district heating (DH) systems that utilise as well the advantages of combined heat and power (CHP) plants.

As a relatively new factor in this context, during the 1980s a number of regional DH systems were established in various parts of Denmark. Their common element is their siting, primarily in areas where several independent DH network systems based on local heat production already existed. These systems have now been interconnected by the regional networks which again are connected to a range of production units.

The Greater Copenhagen Area System

In the Greater Copenhagen area over the last 78 years two transmission systems have been established which have been dimensioned for a net heat capacity of 25,800 TJ/yr, equivalent to the heat demands of approx. 325,000 households. The two companies responsible for the construction activities and overall operation of the networks are CTR, the Metropolitan Copenhagen Heating Transmission Company, supplying a total of five municipalities in central Copenhagen, and the VEKS Heat Transmission Company, supplying 10 municipalities west of the city.

The construction activities on completion have included a total of 150 kilometres of double pipe lines, 65 heat exchanger stations, and 10 booster pumping stations. Furthermore, a total of 4045 peak load stations (mainly rebuilt older units) are at the moment connected to the system a number that will increase to around 50 at full extension of the distribution side in the year 2009.

In addition, a number of 9 different baseload installations consisting of waste incineration plants, other waste treatment plants with energy production, and CHP plants are connected to the systems.

The main tasks for the two transmission companies are the drafting, financing, construction, operation, and ongoing development of transmission systems for DH.

The transmission companies buy heat from the production companies, supplement this if needed with heat from their own peakload and standby plants, transport and distribute the heat through the transmission network, and sell the heat at purchasing points (heat exchanger stations) to associated local distribution companies and other prospective customers.

The above definition of tasks means that the further transportation of heat from the purchasing points to the individual consumers is outside the responsibility of the transmission company and is thus, from here on, in the hands of the associated local supply companies.

Production Capacity

Copenhagen	Net Capacity
CHP Plants	MJ/s heat	MW electric
Amager Power Station 1 Amager Power Station 2 Amager Power Station 3 Avedøre Power Station 1	190 145 330 330	136 128 250 250
Incineration Plants
Amager Incineration Plant Others	40 75
Other
Steam Pool	210
Gas-, Oil, and coal-fired peak-load plants	1,175

As for the CUP production capacity of the networks, two new coalfired steam extraction units have been established recently by the Elkraft Power Company. By the end of 1991 the capacity of the production plants connected to the two transmission systems were as follows:

Optimising of Production

Concerning the cogeneration supplies, an agreement has been made between the two transmission companies and Elkraft to the effect that the production shall be arranged at any time so that the total production costs of the total heat system and power system within a certain period will be as low as possible. It has also been decided that 'the cogeneration advantage' shall be awarded to the heat side during the first 12 years (i.e. until the initial investment has been paid back), after which this advantage is to be divided equally between the heat and power supply side.

Savings

In real figures, this advantage appears as a net energy saving of approx. 360,000 tonnes/ yr of oil. The oil savings gained when the systems are fully implemented have been estimated to be 450,000 tonnes/yr, accompanied by a corresponding lowering of emission levels. For example, sulphur dioxide emission values are to fall by approx. 35%, carbon dioxide by 50%, and nitric oxides by a corresponding value. Furthermore, a reduction of 8090% in the emission of nitric oxides can be obtained at power plants where NO_x reducing equipment has been installed.

Conclusion

Investments in the networks of the two companies total more than DKK 4,500 mill. The primary objective has been to enable surplus heat to be utilised from the area's refuse incineration plants and power stations heat which in the past was just wasted. And, today, less than 10 years after planning commenced, this surplus heat is being widely exploited to benefit the environment and the overall national economy.